Onion tart

Onion tart: slowly softened, melting onions on a thin pastry base, bound with a light egg and milk custard. A rustic, fragrant Alsatian tart where the sweetness of the onion provides all the flavour.

Preparation: 20 min  |  Cooking: 40 min  |  Servings: 6  |  Difficulty: Easy

Calculated per serving from the Anses Ciqual 2025 values for each ingredient, based on the quantities in the list. Household measures (spoonfuls, pieces) use average weights. 234 kcal · 7 g protein · 24 g carbohydrate · 12 g fat

Ingredients

• 1 shortcrust pastry case
• 5 onions
• 2 eggs
• 150 ml milk
• 1 tbsp oil
• 1 pinch of nutmeg
• salt and pepper

Method

1. Slice the onions and soften them for 20 minutes over a low heat.
2. Roll out the pastry and spread the softened onions over it.
3. Beat the eggs, milk, nutmeg, salt and pepper together and pour over the top.
4. Bake for 35 minutes at 180 °C.

Nutritional highlights

Onion, the base of this tart, is rich in antioxidants and prebiotics (fibre that feeds the gut microbiome). With a milk-based custard rather than a cream-based one, and no bacon pieces, this version stays light. A comforting, inexpensive vegetarian lunch.

Variations and substitutions

• Flammekueche style (on a thin base).
• With a little Comté.
• With red onions.
• Semi-wholemeal pastry.

Storage and making ahead

Keeps for 3 days in the fridge; enjoy it hot or cold.

💡 Good to know

Soften the onions over a low heat without letting them colour: it is the long, slow cooking that makes them melting and sweet, which is the whole secret of the tart.

Read more

Discover more vegetarian recipes.

The ingredients in this recipe: pastry · onions · eggs · milk · oil.

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